The present invention relates to a new and improved chemically-dilated, elastomeric sleeve, and more particularly to an improved apparatus for connecting the opposite edges of such a sleeve when it is wrapped around an elongated pipe, cable, conduit, or similar member.
It has been known heretofore that certain types of shrinkable protective tubing may be used for protecting joints, fittings and welds by which pipes, cables, conduits, and other elongated members are joined, one to the other, in an elongated string. One well-known type of material for forming such protective sleeves is a heat shrinkable type, which, when applied over a joint and subjected to heat, shrinks tightly into contact with the members forming the joint.
These types of sleeves and means for connecting them about a pipe, cable or the like are disclosed in the following U.S. Pat. Nos.: 3,379,218; 3,530,898; 4,218,814; 4,241,119; 4,371,578; 4,442,154; 4,532,168; and 4,541,145.
Another type of shrinkable tubing material, and that to which the present invention is particularly addressed, is a shrinkable protective tubing which has been dilated with chemicals to bring the same to a dilated or enlarged state. This type of tubing remains dilated or enlarged so long as it is kept out of contact with the air. However, once the tubing contacts ambient air, it shrinks back to its initial size without any application of heat.
A device for joining the opposite sides of such a sleeve is disclosed in U.S. Pat. No. 4,607,866, also issued to the inventor of the present application. The prior disclosure of this patent is hereby incorporated by reference.
The device disclosed in U.S. Pat. No. 4,607,866 comprises rods that extend through passageways extending along the opposed edges of the sleeve. Alternating and opposing male and female members project from the rods through apertures in the sleeve edges to interlock the rods together, to thus retain the sleeve edges in a juxtaposed position.
These rods, however, are not directly attached to the sleeve, and as such the lock is not as positive as it could be. Additionally, since the sleeves are dilated both longitudinally and laterally, a longer rod is required to accommodate the lateral dilation or expansion of the sleeve. Thus, when the sleeve shrinks, the lock is relatively loose because of use of the longer rod.
Further, the shrinkable protective tubing utilized heretofore has required the use of a "flap". The function of the flap is to prevent any moisture or water from seeping underneath the sleeve through apertures created by the various locking devices. The flap extends below these apertures, protecting the underlying pipe or member from moisture. The inclusion of a flap on the protective tubing not only complicates manufacture but also creates difficulty in the proper placement of the protective tubing or sleeve on a pipe or other member.
The present invention contemplates an improved locking apparatus formed as an extension and integral part of the opposed edges of a chemically-dilated, elastomeric sleeve that shrinks upon exposure to ambient air. The apparatus provides a positive lock that more securely joins the opposed edges of the sleeve. The locking apparatus of the present invention also facilitates installation of the sleeve about in situ piping.
Additionally, the present invention does not require the use of a flap, since no aperture is created by the locking device of the present invention.